Hi, The attached patch changes data structure storing unowned SMgrRelation objects from list structure to hash structure. The reason why I change it is that list structure very slowly removes a node. And list structure takes longer time to remove a node than hash structure.
The problem was reported in BUG #14575. https://www.postgresql.org/message-id/20170303023246.25054.66...@wrigleys.postgresql.org In my customer's case, the standby server was delayed more than 20 minites when dropping many table at once. - Performance check I confirmed the performance of dropping tables by the following method. 1. Set up a synchronous streaming replication environment. And set synchronous_commit = remote_apply in postgresql.conf. 2. Create 100,000 tables (tbl1, tbl2, ... , tbl100000). And insert one row in each table. 3. Measure the time to drop 50 tables by psql $ time psql -d ${DATABSE} -p ${PORT} -f drop.sql drop.sql -- begin; drop table tbl1; drop table tbl2; ... drop table tbl50; commit; -- Result: without this patch real 0m3.734s user 0m0.003s sys 0m0.005s with this patch real 0m1.292s user 0m0.005s sys 0m0.003s Even in this case, we have improved considerably, so I suggest you might approve it. Regards, Takashi Tokuda
change_data_structure_storing_unowned_SMgrRelation.patch
Description: change_data_structure_storing_unowned_SMgrRelation.patch
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